As in the title, how does this work? Or does it work. These calipers, from what I can find, are designed to work with 300mm discs. But these have been fitted 256 mm discs yet it appears as though there is very little, if any, overhang.
Looks like it bolts up, no carriers so if nearer to hub centre then can utilise smaller disc, it's like bolting mk1 fiesta calipers on to a classic mini, they fit under 10" wheels, not the 12 of early fiestas.
Looks a reasonable price for second hand calipers, cheaper than cupra, and Porsche by quick look. Is it standard discs I wonder? Wonder how compare to 280 vr6/g60 set up.
Look like rears by pad springs, this begins the debate on are they any better, like the Porsche rear caliper downgrade discussions. Too much maths for a friday.
It is not the clamp force that is the deciding factor as such, nor is the slightly better radius some of the brake calipers sit at, for example 239 mm discs vs 280 mm discs or even ATE 288 discs, with 20 mm, 22 mm or 23 mm brake masters. It is the friction generated by the pad surface. Of course you also have the suspension and the tyre compound to work with any aggressive pad compound and the temperature the pads begin to effectively work at. Being this is Club GTI, many of us on this forum, track and race our cars from past and present, so we know this from experience and seat time. We are very much a function over form group. Most of the young folks get caught up with a look and can be found running calipers for those extra scene points.
Does anyone know the distance between the mounting holes for 16v/G60 hangers? Is it 76mm or 94mm? Thanks Toyo, I've removed my previous post due to an error in my maths. However this has been corrected in the graph below. For this I've assumed the use of Ferrodo DS2500 pads with a friction coefficient of 0.42 and a brake like pressure of 100 bar, these values aren't important as we are just comparing results. As you can see the Porsche rear setup that has been discussed before is about the same as standard 8v brakes, even though they have smaller piston area thus lower clamping force (orange line) This is possible because the force is acting further out due to the larger disc. However, still not really an upgrade. The Porsche fronts on the other hand are the most powerful, outperforming even G60 brakes. The clamp force doesn't change but the smaller piston size allows the centre of force to be applied closer to the edge of the disc, increasing moment applied to the hub. For these calculations I've assumed there is a 5mm gap between the edge of the piston and the edge of the disc. Now for the Ferrari option. There is very little information for these but I think he would have been using 32/36mm calipers. With that combination you're getting between a 8v and 16v amount of power. As Toyo said, if you want to go for looks, then the fixed calipers are an option. However, even the Porsche fronts which are the most powerful maybe heavier and are definitely more likely to boil the fluid than the floating G60's
You demonstrate the clamping force for different types of calipers, assuming many fixed properties, including crappy DS2500 pads. Pad surface area varies for several of those calipers, except for the Lucas/Girling 54 dia, 256 mm and 280 mm calipers. As does the type of tyre diameter, tyre rubber, braking bias, vehicle weight, suspension and acceleration of the vehicle in a gear. Using pretty powerful Porsche calipers if you can get them to fit, under 15s, with what I would call, "good pad compound" will just lock up the brakes with reasonable brake pressure on a road car with street tyres and maybe a Koni /Eibach suspension. Brembo multi piston calipers do allow more surface area to reject pad friction, although for the road, that is just over kill. Move to a trackday and that whole relationship changes again as you brake harder, later and for a short duration, before getting back on the throttle to navigate the apex of a corner. Such brake components are no good to maintaining the balance and progression of the vehicle before, into and out of a corner. The best balance many of us have found for a MK2 Golf with 15 in wheels and 195 50 tyres, after all the usual internet options, with an 8v to a punchy 20vT are 280 mm Corrado plain disks, 54 piston calipers and carriers, stock textar pads for the road and Ferodo 3000 or CL RC6 for a trackday. Brake master can be 22 dia found on a 16v and brake fluid Super Dot 4 with a high wet boiling point, such as Ate Typ 200. I say stock pads for the road as you will never have to brake late into a corner as you would on a track. I use stock pads on all my road cars, including my 3.2 Turbo Audi 8L S3. As I start pushing on harder and harder on track, brake system cooling begins to become important for repeatable pace, lap after lap, and it is at that time the stock brake system may need a careful rethink. If you have a 1300 kg MK4 Golf GTI or a 1500 kg 4mo 2.8 24v with stock 312 mm ATE brakes and higher spring rates, on track rubber on a 225 40 R17, it does not take long to overheat and warp those after repeatable stabs of the brakes with say DS3000 front pads leading to a corner in the dry. If you have a 1000 kg MK2 Golf or a 850kg MK1 Golf, the same tyre compound and brake pad choice, with a 280 mm disc and Lucas/Girling 54 dia caliper with spring rates to keep the 195 50 R15 rubber pressed into the tarmac, those are probably what most enthusiasts will need without issue. A wet trackday can change vehicle balance too. Often I never bother to change the pads and use my road going Rainsport tyres to just enjoy the day. Caliper looks or clamping force has to be balanced with what the vehicle is used for and what conditions it is used in. There are lots of compromises to have including some mathematics, if you as the enthusiast have justification to alter the stock components.
The aim of my graph was just to show the amount of potential/theoretical braking power available from the different setups. I choose that pad as it is something everyone will know and the line pressure is a best guess, it doesn't really matter what any of the values are as they were kept the same for all of the setups; So the results are still valid for comparison purposes. The pad area is actually irrelevant in terms of braking power which is why is wasn't accounted for. In the real world of course, as you say, there are many more factors at play. Even though a infinitesimally small pad would generate the same friction as a 10 piston Brembo pad, you have to consider the wear and thermal mass and if you can actually manufacture it. And as with any "upgrade" you're always going to need to compromise, in this case its between looks, unsprung mass, thermal mass, cost, serviceability and power. Again, as you said, with a MK2 its easy to go too powerful and upset the brake bias hugely. And thanks for all the information too, especially on track use! As with anything its down to the preference of the individual and the use case of the car.
You achieved your objective with your graph to demonstrate the braking torque or force of different calipers, quite a few, we do not use on Golf chassis vehicles because they represent a backward step in practice, by those who have tried. So you are starting discussion on a topic very well understood practically, by quite a few of us on this group, who have run Lucas/Girling, Brembo and ATE braking systems on these cars and know how they work, wear and generate heat and when they are required to be replaced for alternatives. The beauty of this group is data you generated, can be expressed as practical experience.
Yeah its more of project for myself because I'm not intending on tracking the car really so for me its more about trying something a bit different and out of the ordinary, while still maintaining a good level of performance for a road car. I'm going to take a look a some Calipers next week and I'll post back here if I end up buying them
Track driving vehicles and learning to get the best out of yourself would be the ultimate test for such components in a safe environment. If you have never done so, you will struggle to find the performance limits of such components on a public road, let alone give objective feedback. By all means though, I look forward to how you get on.
I have been to take a look at a set of calipers and I'm going to go again in a few weeks with my wheels to check they fit. I'm also speaking with ATE as they no longer/never released rebuild kits for their Ferrari calipers. Bit of a long shot but I've asked if they will send me the seal diagrams so I can see if I can source my own, I'll see what they say. If not I've got in contact with a few Ferrari breakers to try and source Brembo variants of the calipers which have seal kits readily available.
Update! ATE were very helpful in telling me that themselves nor Ferrari provide rebuild kits for the Calipers and they are unable to provide drawings of the seals for me to have some made. Although Brembo would be the logical choice given this information, the sets I could find had quite a lot of damage and scuffing along with the Ferrari Logo just being a sticker which is a bit of a cop-out. So given that combined with a very good price I decided to purchase these... Taken from a 1995 Ferrari 348 GTB we have two rear calipers! A small scuff to the Ferrari Script on one of them apart from that they look almost new! The cross bolts have some rust on them so I'm currently debating if I want to attempt the removal of them or just leave them, I imagine they're welded in after 25 years! They bolt straight to 16-valve hubs but they are maybe 2-3mm too close to the centre to fit 280 mm discs which is annoying. In order of cost my three options are: Get some custom made single or 2-piece discs made 280mm Vauxhall Meriva discs machined down and balanced to fit 275 mm Toyota Corolla discs with a 3mm spacer behind them and a enlarged centering bore For anyone interested the weight of a G60 caliper and Carrier is around 4.7 KG and the weight of one of these is 2.4 KG.
